Factors which trigger the activation of basophils will be explored. We have recently reported that stimulation of normal peripheral blood lymphocytes results in production of a histamine releasing activity (HRA). This activity will be made in large quantities by lymphocytes obtained by stimulation of thoracic duct cells of patients in preparation for renal allograft. These cells will be used as a source for HRA for further purification and characterization. We will attempt to prepare a monoclonal antibody against HRA in order to improve the speed of purification and to develop a radioimmunoassay. We will further explore development of a guinea pig model to investigate basophil function. The role of antigens, adjuvants and route of administration will be explored in determining the sensitization of basophils.